WINE buffs have uncorked a campaign to banish screw caps from bottles.
The move comes after it was revealed screw caps can leave some wine just as tainted as corks can.

Research carried out for this year's International Wine Challenge - the world's biggest wine competition - found faults caused by screw caps are almost as common as cork taint.

Meanwhile, technological improvements have meant the number of wine bottles spoilt by corks is in decline.
The findings have been seized on by wine traditionalists, who hate screw caps and say cork has served the industry perfectly for hundreds of years.

Screw caps, left, are seen by some wine experts as industrial and lacking the romance of a cork, right, which gives a satisfying pop when the bottle is opened.

However, they have been adopted widely by supermarkets because it was thought there was much less chance of wine going off under a screw cap - a problem said to affect 10% of bottles with corks.

Now tasters at the International Wine Challenge in London claim cork taint is in decline and problems affecting wines sealed with screwcaps have been underestimated.

From a blind tasting of 13,000 wines, they discovered 4% of the wine with corks had faults from oxidation or high sulphide levels - giving it an eggy flavour - compared with 2% of screw-cap bottles.

Robin Garr wrote:From a blind tasting of 13,000 wines, they discovered 4% of the wine with corks had faults from oxidation or high sulphide levels - giving it an eggy flavour - compared with 2% of screw-cap bottles.

So those statistics mean that wines with a screw-cap closure have only half the defect rate of those closed with cork. Sounds like a big win for screw-caps to me.

And what's sulphide got to do with faulty closures? I thought it was completely unrelated. TCA and oxidation are the main cork fault problems, I thought.

Actually, it seems they found twice as many faults in cork-sealed wines as in screwcap-sealed ones. Strange definition of "as much."

My guess is that the majority of the problems with the screwcaps are reductive issues, which seem clearly more a winemaking that closure fault. My impression was with adjustments to winemaking these pretty much disappear.

Paul Winalski wrote:So those statistics mean that wines with a screw-cap closure have only half the defect rate of those closed with cork. Sounds like a big win for screw-caps to me.

The Glasgow article was short and, it seemed, not well researched, but I'm assuming that the IWC study considere 2% and 4% within the statistical margin of error.

And what's sulphide got to do with faulty closures? I thought it was completely unrelated. TCA and oxidation are the main cork fault problems, I thought.

The main screwcap fault production is sulfur-related flaws from reductiveness, and I assumed that was the source of this reference, again perhaps twisted by a reporter without technical knowledge or much skepticism.

"Sam Harrop, a wine-maker who co-chaired the tasting, said that the problem with screwcaps appeared to be related to their greater efficiency as a seal and that companies who had been using them for a long time had all but eradicated the problem.

Jonathan Ray, The Daily Telegraph wine correspondent, said: "In my mind screwcaps are brilliant. They have eliminated almost all cork taint but this shows they are not infallible."

Sulphides ! Phfffft. So is this a new problem?
If you think it is, then ask yourself why on earth you think the copper penny was invented.
Bottom line question to ask - is it the screwcaps or the winemaking?

Robin Garr wrote:The main screwcap fault production is sulfur-related flaws from reductiveness, and I assumed that was the source of this reference, again perhaps twisted by a reporter without technical knowledge or much skepticism.

Well, I suppose that cork-closed wines are less prone to this, since the cork is more likely to leak and let oxygen in to mitigate the reductive problems due to faulty winemaking. So we're to damn screwcaps for doing their job too well, and not covering for faulty winemaking? Methinks not.

Mmm, possibly faulty reasoning there, Paul. The reductive problems have to do with aging wine in an anaerobic environment, and that is in fact a result of the screwcap transmitting much less O2 than natural cork. There may be some ways to address it, but attributing the issue to "faulty winemaking" sinply isn't accurate.

I've seen measurements of oxygen transmission through cork and it sounds as if there's a huge range, from almost none to way too much. And I would say that not preparing a wine for bottling in a way consistent with the closure could certainly be termed 'faulty winemaking.' This problem has been talked about since the AWRI study came out, if not sooner.

But I'm mystified, I drink as many wines as I can from screwcap and I've found very few with reductive aroma; besides, in some areas (the Loire, Alsace, Friuli) many of the wines have needed airing out for as long as I've been drinking them. This isn't new.

Oliver McCrum wrote:I've seen measurements of oxygen transmission through cork and it sounds as if there's a huge range, from almost none to way too much.

I don't think that even the cork industry would deny that, Oliver. With the possibility of a rare statistical outlier, though, it's fair to say that corks transmit some O2 while screwcaps create a more consistently anaerobic environment. I don't think there's any real doubt about this, and so it's no real surprise that reductiveness is an increased issue with screwcaps, at least until the industry finds a consistent way to address it.

And I would say that not preparing a wine for bottling in a way consistent with the closure could certainly be termed 'faulty winemaking.' This problem has been talked about since the AWRI study came out, if not sooner.

Sure, but that's a bit of a semantic game. I interpreted Paul's comment as expressing the opinion that producers are merely putting reductive wine into screwcapped bottles. I doubt that this is so.

But I'm mystified, I drink as many wines as I can from screwcap and I've found very few with reductive aroma; besides, in some areas (the Loire, Alsace, Friuli) many of the wines have needed airing out for as long as I've been drinking them. This isn't new.

I really don't think there's much doubt that wines under screwcap show an increased incidence of reductiveness thanks to the (relatively) anaerobic environment. Unlike TCA, however, reductiveness can be diminished with time, vigorous aeration and/or a copper penny, so it's a bit of a red herring.

Don't shoot the messenger, though. I thought the Glasgow newspaper was interesting, and I suspected it would kick off a good discussion. It wasn't a very well reported or written story, unfortunately, and I'd love to see the IWC's original report.

Mmm, possibly faulty reasoning there, Paul. The reductive problems have to do with aging wine in an anaerobic environment, and that is in fact a result of the screwcap transmitting much less O2 than natural cork. There may be some ways to address it, but attributing the issue to "faulty winemaking" sinply isn't accurate.

Robin,

Could be that, since many of the wines going into screwcapped bottles are on the lesser priced end they are younger and so they are produced in an overly anaerobic manner right up to bottling, perhaps with too vigorous an SO2 regimen, and then the screwcap's anti-oxygen sturcture adds flame to that fire.

Thomas wrote:Could be that, since many of the wines going into screwcapped bottles are on the lesser priced end they are younger and so they are produced in an overly anaerobic manner right up to bottling, perhaps with too vigorous an SO2 regimen, and then the screwcap's anti-oxygen sturcture adds flame to that fire.

Could well be, Thomas ... and also that the types of wines most often put under screwcap - aromatic whites - tend to be wines of relative aromatic and flavor transparency that don't hide reductive flaws behind a curtain of oak and tannins?

If we think about it seriously, the technology challenge of coming up with the perfect container for long-term storage of an organic, evolving product is not trivial, and perhaps we should be amazed that the industry has solved it as well as it has rather than quibbling about the last percentage point or two. It's not a simple thing, and in contrast to the way that these debates generally shake out, it's really not a Manichean battle between good and evil, either.

Robin Garr wrote: If we think about it seriously, the technology challenge of coming up with the perfect container for long-term storage of an organic, evolving product is not trivial, and perhaps we should be amazed that the industry has solved it as well as it has rather than quibbling about the last percentage point or two. It's not a simple thing, and in contrast to the way that these debates generally shake out, it's really not a Manichean battle between good and evil, either.

I quite agree.

It would be interesting to know how many reds and how many whites represent the percentage of reduction under screwcaps and also how many had been produced with oak chips as opposed to the real thing in barrels. Both those parameters could determine the relative anaerobic handling of the wines, and they have nothing to do with the screwcap--they might point to the need for winemakers to learn new limits before bottling for screwcaps.

The 'reduction' problem is widely misunderstood. It's because the very tight seal of the screwcap allows hardly any oxygen transmission, and the reductive environment thus created favours the shift of volatile sulfur compounds from disulfides (which aren't terribly smelly) to mercaptans (very smelly). Thus a wine can be bottled clean, and copper fined (which doesn't take out disulfides) with a screwcap only for some reductive notes to emerge further down the line.

Most people won't spot these because they haven't been trained to spot this reduction, but this doesn't mean it's OK because the wine most certainly isn't reaching the consumer 'the way the winemaker intended'. But it's not as worrying a problem as cork taint, I agree. Still, why should we accept any level of flavour impact from the closure?

Fining in the glass with a copper penny isn't a great solution because it takes out sulfur compounds that can positively contribute to wine aroma.

What do you make of this comment from the Telegraph report of the tasting?

"Sam Harrop, a wine-maker who co-chaired the tasting, said that the problem with screwcaps appeared to be related to their greater efficiency as a seal and that companies who had been using them for a long time had all but eradicated the problem."

I know Sam fairly well - he was responsible for the faults clinic - and I spent some time looking at their procedures during the International Wine Challenge. I think his point is that reduction defects were a significant problem affecting more than 2% of screwcapped bottles. I'm not sure I'd agree with him completely about this being an issue only with inexperienced wineries, but I can see where he's coming from.

The number of bottles where I've had a problem with cork taint has, over the years, been much, much lower than the number of bottles that I've had closed with plastic/synthetic cork that have shown unpleasant plasticky notes in the wine. This, of course, is my personal, subjectively related observation; others' mileage will likely vary.

I recently had a very disappointing experience with a screwcap-closed Chambourcin from a Niagara Winery. I noticed at home that the cap had some mild molasses-looking seepage around the part that snaps off when you twist it open. To my disappointment, the wine turned out to be complete nail polish. I now have become highly wary of this closure for reds. I don't like synthetic corks on reds either.

I've never backed away from holding controversial vinous views, and so in keeping with that tradition, count me as being in favour of the traditional high-quality natural cork (not the cork-dust agglomerate ones, with which I have had high rates of TCA spoilage).

Thomas wrote:Could be that, since many of the wines going into screwcapped bottles are on the lesser priced end they are younger and so they are produced in an overly anaerobic manner right up to bottling, perhaps with too vigorous an SO2 regimen, and then the screwcap's anti-oxygen sturcture adds flame to that fire.

Um, Thomas .... if you look at what is happening in New Zealand, it is wine across all price ranges that are going into screwcap, and the same could be said for Australia too, judging by the number of higher priced Aussie reds I've seen in screwcap lately.
Sue

Sue Courtney wrote:Um, Thomas .... if you look at what is happening in New Zealand, it is wine across all price ranges that are going into screwcap, and the same could be said for Australia too, judging by the number of higher priced Aussie reds I've seen in screwcap lately.

Remember though that this purported data came from entries in the International Wine Challenge in London. I don't doubt that there were some Kiwi and Ozzie wines there, but chances are the proportions aren't the same as they'd be Down Under.